I used Fluid Film on my 1961 Holdsworth.
Mostly because the previous owner(s) let it get a bit rusty and I was determined to stop that ever happening again.
I checked that shootout and Fluid Film won so I found a 11.75oz can on Ebay.co.uk for £16 (last August).

There's also supposed to be a spray hose but I couldn't find one available - most spray hoses won't fit on the Fluid Film can: check carefully.
But you can make a spray hose out of 3mm vinyl tube (2mm ID), just put a screw in the end and cut the sides near the screw.